The Analytical Core will provide analytical support to those components of the project which required the measurement of phospholipids and their derivatives in plasma or tissue. It also provides the analytical support to those projects engaging in the study of protein modification from aging and/or ischemia reperfusion by providing molecular weight and amino acid sequence determination of peptides using electrospray mass spectrometry. This Core enables the PPG investigators to study fatty acids, phospholipids, and modified proteins without the time and monetary costs, expertise, and analytical equipment necessary for undertaking this analysis activity. The specific aims are: 1. Provide gas chromatographic and gas chromatograph-mass spectrometric analysis of fatty acid profiles from non esterified fatty acid fraction as well as from complex lipid fractions (mainly phospholipids) after hydrolysis. 2. Provide silica gel column chromatographic class separation of lipids and high performance liquid chromatographic analysis of phospholipid classes. In addition, the structural confirmation/establishment of unusual acylcarnitines and phospholipids using electrospray mass spectrometry. 3. Provide molecular weight and amino acid sequence determination of modified protein and/or peptides using electrospray mass spectrometry. 4. Provide additional analytical support for those procedures that the Core has the resources and expertise even through the procedures are of limited scope in a particular project. One such example is the high performance liquid chromatographic analysis of 2-mercaptopropionylglycine.